Spin compensating switch for a projectile fuze



May 4, 1965 N. czAJKowsKl 3,181,466

SPIN COMPENSATING SWITCH FOR A PROJECTILE FUZE Filed Feb. 4, 1957 2Sheets-Sheet 1 FIGJ. FIG.2.

l lrllllllll INVENToR N. CZAJKOWSKI 'BY/ wm 7K.

A TYS SPIN COMPENSATING SWITCH FOR A PROJECTILE FUZE Filed Feb. 4, 1957May 4, 1965 N. czAJKowsKl 2 Sheets-Sheet 2 DEFLECTION INVENTOR. N.CZAJKOWSKI 9 M W0' ATTYS United States` Patent Ov 3,181,466 SPINCGWENSATN G SWITCH FOR A PRJECTILE FUZE Norman Czajkowslii, Chevy Chase,Md., assigner to the United States of America as represented by theSeere- Filed Feb. 4, 1957, Ser. No. 638,184

6 Claims. (Cl. 102-70.2)

(Granted under Title 3S, U.S. Code (1952), sec. 266) The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

This invention relates to a centrifugally operated switch for use with aprojectile fuze and more particularly to a centrifugally operated switchwhich is actuated to a closed position when the rate of spin of theprojectile during flight has decreased suiiiciently from the value ofthe initial rate of spin imparted thereto as the projectile is tiredfrom a gun regardless of the maximum value of the initial rate of spin.

The purpose of this invention is to provide a new and improved switchfor an anti-aircraft projectile or spin stabilized rocket, as the casemay be, moveable to a closed position at a predetermined distance fromthe gun controlled by the angle of elevation of the gun at the instantofdiring and which is independent of the initial rate of spin impartedto the projectile by the gun.- As is well known, the difference in rateof spin of projectiles tired from new guns and from old `or worn gunsrespectively varies considerably, the spin in the case of a projectilefired from an old gun being considerably less than the rate of spin ofthe projectile when tired from a new gun.

In devices of this character heretofore devised it has been the usualpractice to employ a reed type switch having a reed Contact elementactuatable to a moved or open position in response to the centrifugalforce initially applied thereto as the projectile is red frorn'the gun.When the rate of spin has decreased to a predetermined value during thetiight of the projectile alonga trajectory the centrifugal force actingon the movable Contact element is reduced to a value suicient to causethe switch to close. This type of switch is usually employed with aprojectile fuzed in such a manner that the fuze is actuated as theswitch closes to eiiect self-destruction of the projectile whereby liveanti-aircraft projectiles or spin stabilized rockets are prevented fromfalling upon friendly troops or material. When employed with aprojectile tired from an old worn gun, such a switch possesses thedisadvantage that the projectile may be self-destroyed before it reachesa target by reason of the low initial spin rate imparted thereto by thegun. Conversely, if the switch is adjusted initially to be employed in aprojectile tired from an old worn gun, such a projectile may fail to heself-destructive when iired from a new gun having a higher spin ratewhereby the live missile may fall upon friendly troops or material.

The device of the present invention possesses all of the advantages ofthe foregoing devices of this general type and none of the foregoingdisadvantages. This desirable result is achieved by automaticallycompensating for variations in the spin rate of the projectile initiallyimparted thereto by a gun. The switch thus operates when thedifferential rate of spin between the initial rate and the rate of spinat which the firing or switch contact is closed has reached a valuecorresponding to a certain predetermined tractional portion of thetrajectory of the projec- Patented May 4, 1955 tile. The manner in whichthis is achieved will be more clearly apparent as the descriptionproceeds. t

One of the objects is to provide a centrifugally actuated switch for aspin projectile in which new and improved means are employed for closingthe switch by a decrease in the rate of spin of the projectile inpredetermined time delayed relation with respect to the tiring of theprojectile from a gun and which is substantially independent of theinitial spin rate imparted thereto by the gun.

Another object is to provide a centrifugally actuated switch for aprojectile fuze in which one of the switch closing elements is settableto a final switch closing position selectively in accordance with themaximum rate of spin applied to the projectile by a gun from Which theprojectile is fired.

Still another object is to provide a centrifugally actuated switch forthe fuze of a spin projectile in which one of the switching elements issettable from an initial closed position to a tiring positionselectively in accordance with the rate of spin initially imparted tothe projectile as the projectile is ired from a gun.

A further object is to provide a new and improved centrifugally actuatedswitch for a spin type missile in which new and improved means areemployed for locking one of the Contact elements of the switch in a ringposition correlative with the maximum spin rate applied to the missile.i

A still further object is to provide a centrifugally operated switch forthe fuze of a spin projectile having new and improved means forpreventing the initial spin rate imparted to the projectile fromadversely aifecting or influencing the proper operation of the switchand its cooperating elements.

Other objects, advantages and improvements will become more clearlyapparent from the following description taken in connection with theaccompanying drawings on which like numerals of reference are employedto designate like parts throughout the several views and in which: j

FiG. 1 is a view partly in section of a prior art switch of the generaltype herein disclosed;

FIG. 2 is a view of the centrifugally operated switch of the presentinvention according to a preferred embodiment thereof on which is shownthe contact elements in an initial closed position;

FiG. 3 is a view similar to FIG. 2 with the switching and lockingelements in a position corresponding to maximum spin rate;

FIG. 4 is a view similar to FIG. 3 of the locking and contact elementswhen the spin rate of FIG. 3 has been somewhat reduced;

FIG. 5 is a view on which is shown the switching elements in a tiringposition;

FIG. 6 is a circuit diagram suitable for use with the switch of FIG. 2;FIG. V7 is a chart on which is shown graphically the deflection of thedatum and contact reeds of the switch when red from an old gun and a newgun, respectively; and

FIG. 8 is a chart on which is shown in graphic form the operationalcharacteristics of the switches of FIGS. l and 2 respectively whenemployed in a projectile fired at 3 different angles of elevation.

Referring now to the drawings for a more complete understanding of theinvention and more particularly to FIG. i thereof there is shown thereona switch of the alegres type heretofore devised and comprising a housingindicated generally by the numeral and having an insulating portion 11secured at one end thereof for supporting a resilient reed type contactmember 12. The inner end of the contact member normally rests against ashoulder 13 on the adjusting screw 14. In operation, the switch is spunby the projectile within which it is mounted in such manner that thecontact member 12 moves away from shoulder 13 by centrifugal force asthe shell is fired from the gun and reengages shoulder 13 when the rateoflspin of the projectile has decreased to a predetermined va ue.

A preferred embodiment of the device of the instant invention is shownon FIG. 2 and indicated generally by the numeral 15, the devicecomprising a housing or casing 16 having end portions 17 and 13respectively, the end portion 18 preferably being composed of metal andsupporting a contact spring member 19 having a Contact 21 aflixedthereto and in normal engagement with a resilient reed type contact 22.The contact reed 22 is insulated from the end portion 18 in any suitablemanner and is provided with a terminal 23 for establishing an externalelectric circuit thereto. A rod 24 is threaded as at 25 into the casing16 substantially as shown and provided preferably with a slot 26 wherebythe rod may be moved to a predetermined adjusted position within thecasing by means of a suitable tool. A locking Washer 27 having anaperture therein of slightly greater size than the rod 24 is slideablycarried by the rod and normally held against a shoulder 28 by thecontact spring member, hereinafter referred to as the datum member 19substantially as shown. The reed contact element 22 is initiallytensioned against the contact 20, this preloading being sufficient tomaintain good electrical conductivity between the members 19, 22, andpressure against the locking member 27 is such that the lock mechanismis restrained against movement due to rough handling.

The operation of the switch of FIG. 2 will now be described. Let it beassumed, by way of example, that the switch is mounted within aprojectile in such manner that the rod 241 is normal to the axis of spinthereof and that the axis of spin of the projectile is below the bottomportion of the rod 24 as viewed in the drawing. As the projectile isired from a gun, the centrifugal force imparted thereto by the gunriiling causes the contact spring members 19 and 22 and the lockingwasher 27 to be moved to a position by centrifugal force such as shownon FIG. 3, the reed type contact member 22 moving through a greaterdistance than the datum contact member 19 by reason of the fact that thecontact members 19 and 21 possess dierent spring constants. As thecontact spring 22 is disengaged from contact 21 the terminal 23 thereofis disconnected from ground.

As the rate of spin decreases during the flight of the projectilecontact springs 19 and 22 move towards their initial positions by reasonof the preloading tension of the springs. When this occurs the lockingmember 27 is tilted, as shown in FIG. 4, into locking engagement withthe rod 24 and further inward movement of the datum spring 19 is thusprevented. As the spin rate decreases further, however, the reed typecontact spring 22 continues to move toward the initial position untilthe rate of spin has decreased to a value such as to cause the contactelement 22 to engage contact 21, FIG. 5. When this occurs ground isagain applied to terminal 23 of contact element 22.

From the foregoing it will be understood that the locking member 27 ismoved to a locking position along the rod 24 correlative with themaximum rate of spin of the projectile at the instant of leaving themuzzle of the gun. The datum spring 19 is thus locked in a finalposition correlative with the maximum spin rate of the missile and thedelay in closing the switch contacts thereafter is thus correlativo withthe distance which the missile has traveled from the gun, the distancebeing related to the time of travel of the missile during flightrequired for the reed type contact 22 to move from the position Shown inFIG. 3 to the closing or tiring position of FIG. 5.

Obviously if the projectile is iired from a new gun the position of thecontact member 19 and locking member 27 will be moved further from theinitial position thereof as the projectile leaves the muzzle of the gunby reason of the high spin rate and, conversely, if the missile wasfired from an old worn gun these elements would be moved a lesserdistance from the initial position thereof by reason of the decreasedrate of spin. In the rst case assumed, the locking member would belocked further along the rod 24 and thus the closing or tiring positionof the switch would be moved further from the initial position thereofand the switch would be closed at a higher rate of spin than would bethe case if the missile was tired from an old worn gun.

This condition will be more readily understood by reference to FIG. 7 onwhich is shown two curves 29 and 31 representing deflections of thecontact and datum reeds respectively over a spin range of 0 to 675revolutions per second. If it be assumed that the maximum spin of theprojectile fired from an old gun is 5 32 revolutions per second, thedatum reed will be moved and locked at point 32 of curve 31 and thecontact reed will be moved to the point 33 of curve 29. The switchcontacts are now open. Since the rate of spin of the projectile hasdecreased to 392 revolutions per second, the contact reed will be in aposition indicated by the numeral 34 and engage the contact 21 of thedatum reed.

When, however, the missile is red from a new gun having a maximum rateof spin of 630 r.p.s. applied thereto by the gun the datum and contactreeds will be moved to the points 35 and 36 respectively, the datum reedbeing locked at this position by the locking washer 27. When the rate ofspin has decreased to 462 r.p.s. the contact reed will be moved toposition 37 and engage contact 21 of the datum reed.

The correlation between this operation of the switch and the range atwhich the switch operates to close its contacts is shown on FIG. S ingraphic form for three different angles of elevation of the gun. Thereis also shown on this figure ranges corresponding to the prior artswitch of FIG. 1 and -a comparison of the timed operation of theseswitches when the projectile in which the switches are carried is redfrom an old gun and a new gun respectively. The curve 38 is employed toindicate both the maximum altitude and range of a projectile tired fromthe gun at 10 degree elevation. Considering now the case where theprojectile is tired from an old gun and the projectile is provided withthe switch of FIG. l, the operation of the switch is indicated generallyby the dark portion 39 of the curve and when red by a new gun by thelight portion 41 of this curve. There is also shown by the darkenedportion 42 of curve 38 the operation of the switch of FIG. 2 whenemployed with an old gun and by the darkened portion 43 the operation ofthe switch of FG. 2 when employed with a new gun. It will thus beclearly apparent from an inspection of the figure that the secondclosure of the switch of the instant invention occurs at substantiallythe same point on the trajectory regardless of the initial rate of spinimparted to the projectile by the gun in contradistinctiou to the widevariation in range at which the switch of FIG. l operates when employedwith old and with new guns.

Curves 44 and 45 are generally similar to curve 38, these curvesillustrating the performance of the centrifugal switches of the instantinvention and the prior art when fired from a gun of 40 degrees and 70degrees elevation respectively. The operation of applicants switch whenemployed with an old gun at an elevation of 40 degrees is shown at i6and when employed with a new gun at 47. When the angle of the gun iselevated to 70 degrees the operation of applicants switch with an oldgun is shown at 48 and when used with a new gun at 49.

The switch of the present invention is well adapted for use inself-destruction of a missile in flight. When so employed it may beconnected in any suitable mannerV to achieve this result, a circuitsuitable for this purpose being shown on FIG. 6 to which attention isnow directed.

A thyratron tube 51 has the control element thereof operativelyconnected to the output of the amplifier of a proximity fuze, forexample, the plate thereof being connected to a firing condenser Candterminal 23 of applicants switch. The plate is also connected by Way of'high resistance R to the positive terminal of battery B. The oppositeterminal of condenser C is connected to the primer P and thence toground, the primer P being shunted by a shorting Wire or switchingelement 52. The filament of the tube is energized by battery A.Batteries A and B, as is well known, are the type adapted to beactivated in response to setback force as the missile is fired from thegun. Ground is applied to the various components of the circuit asshown.

As the projectile is fired from the gun and reed type contact 22. isdisengaged from contact 21, the shunt circuit is removed from thecharging condenser C and the primer P. The energization of battery Bcauses a charging cur-V rent to flow through R sufficient to chargecondenser C to a firing potential, the primer P being prevented fromoperating rby the switch 52 connected thereacross. When sufficient timehas elapsed for condenser C to become fully charged, the switch 52 isopened by a fuze safety device [not shown] which may be of any wellknown type and the fuze is armed and ready for operation by tube 51 orthe centrifugally operated switch, as the case may be. If the projectilemoves to a position sufficiently close to the target tube 51 is operatedthereby causing the primer to be fired by discharging current fromcondenser C and explode the missile. If, on the other hand, the missiledoes not come within lethal range of target before the centrifugal forcehas decreased to a value sufficient to cause contact spring Z2 to moveinto engagement withV contact 21, the operation of the centrifugalswitch causes the primer to be tired by discharge current from condenserC.

Bniey stated in summary the present invention provides a centrifugallyoperated switch for use with a spin type missile having means forcompensating for variations in the initial spin rate imparted to themissile by the gun in such manner that the switch contacts are closedwhen the rate of spin of the projectile has decreased to a valuecontrolled by a locking device set to an initial locking positioncorresponding to the maximum rate of rotation of the missile.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A spin compensating centrifugal switch for use with a spin typeproject-ile comprising a casing, a lock shaft disposed within saidcasing and having a shoulder thereon, a circular locking memberslideably carried by said shaft and having an aperture therein ofslightly greater diameter than the shaft within which the shaft isdisposed, a datum reed secured to one end of the casing at an endportion thereof in such manner that the other end of the reed yieldablyurges said locking member into engagement with said shoulder, a contactreed of greater flexibility than the datum reed carried by said endportion of the casing and normally engaging said datum reed and aterminal on said contact reed for establishing an external electricalconnection thereto.

2. A centrifugally operated switch of the character disclosed for usewith a spin type projectile comprising a casing, a locking shaftdisposed transversely within said casing and normal to the axis of spinof the projectile, a datum reed carried by said casing and having an endportion in closely spaced relation to said shaft, stop means on saidshaft, a locking Washer having an aperture therein of slightly greaterdiameter than the shaft within which the shaft is disposed, said washerbeing arranged between the end of said datum reed and said stop meansand normally urged against the stop means by the datum reed, a contacton an end portion of said datum reed, a flexible contact reed carried bysaid casing and insulated therefrom in such manner that the contact reednormally is in predetermined preloaded engagement with said datum reedcontact, said contact and datum reeds having different spring constantssuch that the contact reed is moved ou-t of engagement with the datumreed contact in response to centrifugal force when the projectile is redfrom a gun, the axis o-f said shaft being normal to the spinV axis ofthe projectile whereby the locking washer is moved along said shaft andlocked thereto in a cocked position by said datum reed as the projectilespin decreases from a maximum value and the contact reed moves intoengagement with the locked datum reed in response to a further decreasein the rate of spin.

3. A centrifugally operated switch for use with a spin projectilecomprising a pair of normally closed contact elements carried by aContact reed and a datum reed respectively, each yof said reeds beingconstructed and arranged to be moved from an initial closed contactposition to a moved position by centrifugal force acting thereon as theprojectile is fired from a gun, means controlled by the rate of spin ofthe projectile for locking said datum reed in a firing positioncorrelativo with the maximum rate of said spin, said contact and datumreeds having different spring constants whereby the contact element ofthe contact reed is disengaged from the contact element of the datumreed in response to the initial spin of the projectile as the projectileis red from a gun and .the contact of the contact reed is moved intocircuit closing position with respect to the contact of the locked datumreed as the spin rate of the projectile is decreased by a predeterminedamount from the maximum rate of spin.

4. A switch according to claim 3 in which means threadedly engaging saidswitch is provided for adjusting at will the initial position of saiddatum and contact reeds.

5. A switch according to claim 3 in which said locking means comprises alocking shaft having a slideable locking member thereon adapted to bemoved from an initial position of rest to a final position correlativawith the maximum rate of spin of the projectile in response tocentrifugal force and to be cocked in said nal position in lockingengagement with said shaft by the datum reed as the spin rate isdecreased from said maximum rate.

6. In a spin missile adapted to be red from a gun, the combination of acasing, a ythreaded locking shaft disposed within said casing and havinga shoulder thereon, an annular locking disc encircling and slideablycarried by said shaft and adapted to be locked thereto selectively indifferent positions when moved into cocked engagement therewith, a datumreed carried by said casing and having one end thereof yieldably urgingsaid locking disc against said shoulder, a Contact on said datum reednear the free end thereof, a contact reed carried by said casing andinsulated therefrom, said contact reed being preloaded into initialengagement with the contact on said datum reed and having a terminal forestablishing an external electrical connection thereto, said contact anddatum reeds having different spring constants such that Ithe contactreed is disengaged from said datum reed contact and both reeds aretiexed in a direction away from said shoulder by centrifugal force asthe missile is tired from a gun, said contact reed deflecting a greateramount than the datum reed and the locking disc following the datum reedalo-ng said shaft whereby the datum reed is locked at the limit of exurethereof by said locking disc as the 7 8 centrifugal force decreases andthe disc is moved into References Cited by the Examiner cockedengagement with said shaft, a ring circuit for UNITED STATES PATENTSsaid missile and means operatively connecting said firing F circuit tosaid terminal whereby the firing circuit is closed lm-a-n When the rateof spin of the missile has decreased to a 5 value corresponding to therate required to move the contact on the contact reed to a firingposition in engage- SAMUEL FEINBERG P" mary Examiner' ment with theContact on said datum reed. SAMUEL BOYD, Examiner.

3. A CENTRIFUGALLY OPERATED SWITCH FOR USE WITH A SPIN PROJECTILECOMPRISING A PAIR OF NORMALLY CLOSED CONTACT ELEMENTS CARRIED BY ACONTACT REED AND A DATUM REED RESPECTIVELY, EACH OF SAID REEDS BEINGCONSTRUCTED AND ARRANGED TO BE MOVED FROM AN INITIAL CLOSED CONTACTPOSITION TO A MOVED POSITION BY CENTRIFUGAL FORCE ACTING THEREON AS THEPROJECTILE IS FIRED FROM A GUN, MEANS CONTROLLED BY THE RATE OF SPIN OFTHE PROJECTILE FOR LOCKING SAID DATUM REED IN A FIRING POSITIONCORRELATIVE WITH THE MAXIMUM RATE OF SAID SPIN, SAID CONTACT AND DATUMREEDS HAVING DIFFERENT SPRING CONSTANTS WHEREBY TE CONTACT ELEMENT OFTHE CONTACT REED IS DISENGAGED FROM THE CONTACT ELEMENT OF THE DATUMREED IN RESPONSE TO THE INITIAL SPIN OF THE PROJECTILE AS THE PROJECTILEIS FIRED FROM A GUN AND THE CONTACT OF THE CONTACT REED IS MOVED INTOCIRCUIT CLOSING POSITION WITH RESPECT TO THE CONTACT OF THE LOCKED DATUMREED AS THE SPIN RATE OF THE PROJECTILE IS DECREASED BY A PREDETERMINEDAMOUNT FROM THE MAXIMUM RATE OF SPIN.